Справка LibreOffice 24.2
If you double-click a connection between two linked fields in the query design, or if you choose Insert - New Relation, the Join Properties dialog appears. These properties will be used in all queries created in the future.
Specifies two different tables that you want to join.
Specifies two data fields that will be joined by a relation.
Specifies the join type of the selected join. Some databases support only a subset of the various possible types.
In an inner join, the results table contains only those records for which the content of the linked fields is the same. In LibreOffice SQL this type of link is created by a corresponding WHERE clause.
In a left join, the results table contains all records of the queried fields from the left table and only those records of the queried fields from the right table for which the content of the linked fields is the same. In LibreOffice SQL this type of link corresponds to the LEFT OUTER JOIN command.
In a right join, the results table contains all records of the queried fields from the right table and only those records of the queried fields from the left table for which the content of the linked fields is the same. In LibreOffice SQL this type of link corresponds to the RIGHT OUTER JOIN command.
In a full join, the results table contains all records of the queried fields from the left and right tables. In the SQL of LibreOffice this type of link corresponds to the FULL OUTER JOIN command.
In a natural join, the keyword NATURAL is inserted into the SQL statement that defines the relation. The relation joins all columns that have the same column name in both tables. The resulting joined table contains only one column for each pair of equally named columns.